White matter damage may trigger early neurodegenerative changes, suggests Cambridge study

Damage to the brain’s white matter can set off changes linked to neurodegenerative diseases such as Alzheimer’s and Parkinson’s, according to a new study published in Nature by researchers at the University of Cambridge.

The findings challenge long-held assumptions that such diseases are driven primarily by damage to grey matter. The study suggests that targeting white matter injury and repair could reshape treatment strategies, an insight with implications for conditions marked by progressive brain decline.

The brain is composed of roughly equal parts grey and white matter. While grey matter houses processing centres, white matter forms the communication network linking them. Although white matter damage is known to occur in disorders such as multiple sclerosis and is also observed in Alzheimer’s and Parkinson’s disease, its broader impact has remained unclear.

The research team, led by Ragnhildur Thóra Káradóttir at Cambridge’s Stem Cell Institute, induced localised damage to myelin, a key component of white matter, within a defined brain circuit. They tracked how this injury influenced connected regions over time.

The study found that even small, localised myelin damage triggered significant changes in distant grey matter. Neuronal activity dropped, immune cells known as microglia were activated, and connections between neurons weakened.

Importantly, these effects were reversible. Once myelin regenerated, neuronal activity returned to normal, neural connections were restored and inflammation subsided.

The findings also revise understanding of brain inflammation. Rather than being purely harmful, transient inflammation in grey matter appeared to support repair. When researchers blocked this inflammatory response, myelin regeneration was impaired. Conversely, when myelin repair was prevented, inflammation persisted and became chronic.

Professor Káradóttir noted that white matter injury is not an isolated event but can trigger coordinated responses across the brain, forming part of its intrinsic repair mechanism. The study further suggests that failure of myelin regeneration may contribute to the sustained low-grade inflammation seen in neurodegenerative diseases.

Alasdair Coles, Professor of Clinical Neuroimmunology at Cambridge, said the findings point towards therapies that enhance myelin repair as a potential way to slow disease progression across a range of neurological disorders.

The study offers a new framework linking local white matter damage to widespread brain dysfunction. It underscores the need to look beyond grey matter in understanding and treating neurodegenerative diseases, particularly in conditions such as multiple sclerosis where white matter injury and incomplete repair are central to disease progression.